To fell and process trees, an operator may use a tree harvester having a harvester head moveably coupled to a wheeled or tracked chassis via a boom assembly. In use, the harvester head grips an upright, growing tree and cuts or fells it. Then, while driving the felled tree trunk longitudinally through the harvester head, the harvester head delimbs branches from the felled tree trunk. The harvester head may also be configured to chop the delimbed tree trunk into shorter pieces with a chain saw or another suitable cutting device. If the harvester head includes an accumulation pocket, the head may also hold multiple felled tree trunks. Finally, the harvester head places the felled tree trunks in bunches on the ground for further processing.